SCCM WSUS Sync fails with HTTP 503 errors

In this post we will see how to deal with SCCM WSUS Sync fails with HTTP 503 errors. Recently one of the customer reported issues related to software updates. They were unable to synchronize their Software Update Point with their WSUS server. They mentioned that updates synchronization worked fine before. When i looked into this issue, i found some errors in wsyncmgr.log and WCM.log file. The customer was using SCCM 2012 R2 SP1 with CU3. The error was “The request failed with HTTP status 503 Service Unavailable”.

I noticed that when i rebooted the primary site server, the updates started synchronizing well. But after sometime, even i noticed that updates synchronization failed. I ensured that WSUS service was running in services console. In addition browsing http://sccmserver:8530 showed HTTP Error 503. The service is unavailable.

Note – So how did i resolve this issue ?. Well, there is one old article by Microsoft on this issue. I read the article and found that it was exactly the same issue as I was working on. In my case WSUS sync failed with HTTP 503 errors and indeed the resolution mentioned in this article worked fine for me. If you read out the comments section, you will notice that the solution worked for many.

Errors logged in wsyncmgr.log file are shown below. Notice that the lines in log file says that WSUS server not configured. As WSUS was configured correctly, therefore this error was incorrect. Furthermore another line said check WCM.log file for more errors.

Checking the WCM.log file, I found some errors. The request failed with HTTP status 503 Service Unavailable. That was the error and it also said remote configuration failed on WSUS server. At this point one might be thinking to uninstall SUP and install it back. Or probably reinstall WSUS and configure SUP again. Wait, there are some steps that you can try and fix this issue.

SCCM WSUS Sync fails with HTTP 503 errors

If you are dealing with SCCM WSUS Sync fails with HTTP 503 errors, you can try out the below steps. In this example the SUP and WSUS was installed and configured on the primary site server. As per article by Microsoft, most likely cause of this issue is WsusPool Application Pool in IIS is in a stopped state. That was correct, the WsusPool was in stopped state. Click WsusPool and on actions pane, under Application Pool tasks, click Start.

Now that you have started Wsuspool, click Advanced Settings on the right pane.

Look for Private Memory Limit (KB) and you will notice that default value is 1843200 KB. You must increase the Private Memory Limit to 4GB (4000000 KB) and restart the Application Pool. To change the private memory limit, enter the value 4000000 and click OK. While 4000000 KB may not be sufficient for large environment, you can increase the value to 8000000 KB.

After you perform the above steps, click WsusPool and click Recycle. In SCCM console, click Synchronize software updates. The software updates sync should work fine now. Let me know if the steps worked fine for you in the comments section.